Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
CMP
Credit: Jack Hobhouse

Shilei Zhang

Long Term Visitor

Sub department

  • Condensed Matter Physics
shilei.zhang@physics.ox.ac.uk
Telephone: 01865 (2)72317
Clarendon Laboratory, room 261
  • About
  • Publications

Magnetization dynamics in ordered spin structures revealed by diffractive and reflectometry ferromagnetic resonance

AIP Advances American Institute of Physics 11:1 (2021) 15327

Authors:

Dm Burn, Shilei Zhang, G van der Laan, T Hesjedal

Abstract:

Synchrotron radiation based techniques provide unique insight into both the element and time resolved magnetization behavior in magnetic spin systems. Here, we highlight the power of two recent developments, utilizing x-ray scattering techniques to reveal the precessional magnetization dynamics of ordered spin structures in the GHz regime, both in diffraction and reflection configurations. Our recently developed diffraction and reflectometry ferromagnetic resonance (DFMR and RFMR) techniques provide novel ways to explore the dynamics of modern magnetic materials, thereby opening up new pathways for the development of spintronic devices. In this paper we provide an overview of these techniques, and discuss the new understanding they provide into the magnetization dynamics in the chiral magnetic structure in Y-type hexaferrite and the depth dependence to the magnetization dynamics in a [CoFeB/MgO/Ta]4 multilayer.
More details from the publisher
Details from ORA
More details

Skyrmions getting an X-ray

MagNews UK Magnetics Society 2019:3 (2020) 22-22

Authors:

Shilei Zhang, Thorsten Hesjedal, Gerrit van der Laan
Details from ORA

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Proceedings of the National Academy of Sciences National Academy of Sciences 115:25 (2018) 6386-6391

Authors:

Shilei Zhang, G van der Laan, J Mueller, L Heinen, M Garst, A Bauer, H Berger, C Pfleiderer, Thorsten Hesjedal

Abstract:

It is commonly assumed that surfaces modify the properties of stable materials within the top few atomic layers of a bulk specimen only. Exploiting the polarization dependence of resonant elastic X-ray scattering to go beyond conventional diffraction and imaging techniques, we have determined the depth dependence of the full 3D spin structure of skyrmions—that is, topologically nontrivial whirls of the magnetization—below the surface of a bulk sample of Cu2OSeO3. We found that the skyrmions change exponentially from pure Néel- to pure Bloch-twisting over a distance of several hundred nanometers between the surface and the bulk, respectively. Though qualitatively consistent with theory, the strength of the Néel-twisting at the surface and the length scale of the variation observed experimentally exceed material-specific modeling substantially. In view of the exceptionally complete quantitative theoretical account of the magnetic rigidities and associated static and dynamic properties of skyrmions in Cu2OSeO3 and related materials, we conclude that subtle changes of the materials properties must exist at distances up to several hundred atomic layers into the bulk, which originate in the presence of the surface. This has far-reaching implications for the creation of skyrmions in surface-dominated systems and identifies, more generally, surface-induced gradual variations deep within a bulk material and their impact on tailored functionalities as an unchartered scientific territory.
More details from the publisher
Details from ORA
More details
More details

Direct observation of twisted surface Skyrmions in bulk crystals

Physical Review Letters American Physical Society 120:22 (2018) 227202

Authors:

Shipeng Zhang, G van der Laan, WW Wang, A Haghighirad, Thorsten Hesjedal

Abstract:

Magnetic skyrmions in noncentrosymmetric helimagnets with Dn symmetry are Bloch-type magnetization swirls with a helicity angle of ±90∘. At the surface of helimagnetic thin films below a critical thickness, a twisted skyrmion state with arbitrary helicity angle has been proposed, however, its direct experimental observation has remained elusive. Here, we show that circularly polarized resonant elastic x-ray scattering is able to unambiguously measure the helicity angle of surface skyrmions, providing direct experimental evidence that a twisted skyrmion surface state also exists in bulk systems. The exact surface helicity angles of twisted skyrmions for both left- and right-handed chiral bulk Cu2OSeO3, in the single as well as in the multidomain skyrmion lattice state, are determined, revealing their detailed internal structure. Our findings suggest that a skyrmion surface reconstruction is a universal phenomenon, stemming from the breaking of translational symmetry at the interface.
More details from the publisher
Details from ORA
More details
More details

Manipulation of skyrmion motion by magnetic field gradients

Nature Communications Springer Nature 9 (2018) 2115

Authors:

SL Zhang, WW Wang, DM Burn, H Peng, H Berger, A Bauer, C Pfleiderer, G van der Laan, Thorsten Hesjedal

Abstract:

Magnetic skyrmions are particle-like, topologically protected magnetisation entities that are promising candidates as information carriers in racetrack memory. The transport of skyrmions in a shift-register-like fashion is crucial for their embodiment in practical devices. Here, we demonstrate that chiral skyrmions in Cu2OSeO3 can be effectively manipulated under the influence of a magnetic field gradient. In a radial field gradient, skyrmions were found to rotate collectively, following a given velocity–radius relationship. As a result of this relationship, and in competition with the elastic properties of the skyrmion lattice, the rotating ensemble disintegrates into a shell-like structure of discrete circular racetracks. Upon reversing the field direction, the rotation sense reverses. Field gradients therefore offer an effective handle for the fine control of skyrmion motion, which is inherently driven by magnon currents. In this scheme, no local electric currents are needed, thus presenting a different approach to shift-register-type operations based on spin transfer torque.
More details from the publisher
Details from ORA
More details
More details

Pagination

  • Current page 1
  • Page 2
  • Page 3
  • Page 4
  • Page 5
  • Page 6
  • Page 7
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet